Unknown debit card transaction

I've recently got a UFJ Visa debit card which sends me emails whenever it's used. Today I got an email saying it was used while I was at work which obviously concerned me and I logged on to see that money had gone out of my account. Unfortunately the transaction history only ever seems to say "visa debit" and nothing helpful like who took the money or where from. Is there any way to find this out or do debit card transactions only ever say "Visa Debit"?

Go to your local branch and ask?

that was my thought too but the banks are always closed when i finish work and my Japanese isn't good enough to call on the phone.

How much was the charge? And have you been using the card for other transactions as sometimes they may not post immediately.

call 0120-860-735, then select No.2.
you can call from 9:00 to 17:00 all days (including holidays).
ask your intimate Japanese friend help calling.
there is an insurance for unknown withdrawals.

if you log on the visa debit memer web site, you can know the details of withdrawals.
http://www.bk.mufg.jp/tsukau/visadebit/moushikomi/member_web.html

Nope, I've only had the card 2 weeks and used it 4 times.
The charge was 130k.

I logged on to the direct site and it shows all the transactions i expected and the rogue one but all (even the ones I did) just say "Visa debit" in the description with no info on who/where/etc

If it is a fraudulent charge, you're going to have to either call or go in person one way or the other anyway, so you might as well do that regardless. You can probably take off work for that reason for an hour or two during the day to go to the bank, as that is what many Japanese have to do when they work a full-time job. Random people on an internet forum are not going to be able to help you with this, and if you don't recognize the charge as one you did, then it's probably fraudulent and we can't help with that either.

Scarreddragon is right. In any case, you should have your card canceled as soon as possible, which can be done by phone. It's a common crime. You should take it very seriously, which is the reason employers typically let's you take a day off.